1. Written language - Numbers were most likely the first written language. Legends can be passed on orally and a little variation by the storyteller is as likely to add quality to the story as to detract from it. A little variation in recounting business deals gets people mighty unhappy.

2. Printing press - Communication allows one to build on the ideas of others. Example, after Rene Descartes invented the Cartesian coordinate system, both Newton and Leibniz quickly invented Calculus independently of each other.

3. Radio - Same reason as above.

4. Computers & Internet - Same reason as above, except even more so. The rapid spread of information probably prevents anyone being seen as the equivalent of Newton or Einstein, since almost no one develops new ideas alone from start to finish, anymore.

5. Railroads - The first rapid transportation accelerated the industrial age. Transportation was so important that railroads drove the development of the first standardized time zones.

OH, and slide rules, of course. Well, at least Napier's method of logarithms was pretty important, which is the principle that slide rules are based on.

4./ George Foreman's Lean Mean Fat Reducing Grilling Machine... so good he puts his NAME on it!

:rofl: :rofl: :rofl: I bought one of those for Tsu and she looked at me like I had given her a set of wrenches; until she used it once. They really are pretty handy, especially for little spraymaster skunks it turns out...oh wait...I mean chickens.

Some may recall that a large group of experts from many fields of study voted that the printing press is the most significant invention of the last 1000 years. This made most other advancements possible.